Bore hole tool with magnetic blade retention

ABSTRACT

A bore hole tool which uses magnetic means to retain the tool in a closed or collapsed position when in a non-operating mode while able to release from the magnetic retention to an open or enlarged position when said tool is in an operating mode when rotation is applied or fluid is pumped through said tool.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional patent applicationSer. No. 61/271,414 filed Jul. 21, 2009 by Alan L. Nackerud, which isincorporated by reference herein.

BACKGROUND AND FIELD OF INVENTION

This invention generally relates to bore hole tools, including, but notlimited to underreamers, section mills, casing cutters, casing scrapersand drill string centralizers, hereinafter collectively referred to asBore Hole Tool(s). Most conventional Bore Hole Tools which expand indiameter when operating have expandable blades or cutters which areopened by pump pressure and returned to a closed position by a spring orother mechanical retraction device when not in use. However, some BoreHole Tools do not have a spring or other mechanical retraction devicefor said blades but rather are free to rotate on their axis at any time,and are activated or opened when fluid is pumped and expelled throughthe blades and/or rotation of the drill string is applied. In a verticalwell bore the Bore Hole Tool blades close by gravity upon cessation ofpumping and cessation of rotation which allows the drill string to beadvanced or retracted within the bore hole without the blade or bladescatching the side walls of the well bore. One problem with said toolswithout a mechanical retraction device is that in a horizontal or angledwell bore they do not always readily close or remain in a closedposition when desired due to gravity pulling the rotatable downwardblade against the well bore sidewall. Advancement or retraction of thedrill string in a non-operating mode can thereby be problematic. Thepresent invention is an improvement to said Bore Hole Tools andalleviates this problem by having one or more retention magnetspositioned in the body or blades such to keep the blades in a closedposition when fluid is not being pumped through the drill string and thedrill string is not being rotated. At least one full slow rotation ofthe drill string allows the blade or blades to close into the bodywhereby the retention magnets keep the blades retracted in the body in anon-operating mode. The retention magnets are of a predeterminedsufficient strength to keep the blades in a closed position when fluidis not being pumped through the drill string and the drill string is notbeing rotated, however said magnets are of a predetermined limitedstrength which allows the blades to open upon sufficient pumping orrotation. The present invention thereby allows the drill string and BoreHole Tool to advance or retract within the bore hole when in anon-operating mode.

SUMMARY OF THE INVENTION

The above and other advantages and features will become more readilyappreciated and understood from a consideration of the followingdetailed description of different embodiments when taken together withthe accompanying drawings in which:

DRAWINGS-FIGURES

FIG. 1 is a side view of assembled tool in closed position;

FIG. 2 is a side view of assembled tool in closed position rotated 90degrees;

FIG. 3 is a section view of assembled tool through the magneticretention device with blades in a closed position;

FIG. 4 is a side view of assembled tool in an open position;

DRAWINGS-REFERENCE NUMERALS

-   10. body-   11. blade one-   12. blade two-   13. blade one magnet-   14. blade one magnet opening-   15. blade one magnet encasement material-   16. blade two magnet-   17. blade two magnet opening-   18. blade two magnet encasement material-   19. blade cutters-   20. blade fluid ports-   21. blades slot-   22. blades main fluid bores-   23. body main fluid bores

DETAILED DESCRIPTION

Referring to the drawings, there is illustrated in

FIGS. 1 through 4 one form of the present invention being an improvedBore Hole Tool with magnets 13, 16 for steel blades 11, 12 retention inthe body 10 when the Bore Hole Tool is in a closed position and in anon-operating mode. In FIG. 1 the Bore Hole Tool has a top threadedconnection and a bottom threaded connection to allow connection to adrill string. The Bore Hole Tool has a bore through the top threadedconnection. Said bore intersects angled bores in the body 10 which leadto and intersect body main fluid bores 23 which run down both sides ofthe body 10 which then intersect angled bores back into a bore leadingout the bottom threaded connection and into the preceding drill stringand any preceding bottom hole assembly. The Bore Hole Tool body mainfluid bores 23 also intersect bores into blades 11, 12 and main fluidblade bores 22 whereby fluid can travel into and through blades 11, 12and expel out blade fluid ports 20 which assist the Bore Hole Toolopening. The blades 11, 12 are free to move on their pin or bearing axisnear the top of the Bore Hole Tool whereby rotation of the drill stringallows centrifugal force to also assist opening of the Bore Hole Toolblades 11, 12. When the Bore Hole Tool is in a non-operating mode,retraction of the blades 11, 12 back into the Bore Hole Tool body 10 iscaused by cessation of pumping fluid and cessation of rotation of thedrill string whereby gravity causes the blades to close by gravity in avertical well bore. In an angled or horizontal well bore, closure of theblades 11, 12 is assisted by one or more slow rotations of the drillstring whereby gravity cause the blades 11, 12 to retract into the body10. The blades remain in a closed or retracted position by one or moremagnets 13, 16 which are placed in the magnet openings 14, 17 in thebody 10. This is especially helpful when the Bore Hole Tool is workingin an angled or horizontal well bore where gravity would otherwise pullthe blade able to rotate downward to an open position whereby it maycatch the side wall of the well bore. The magnets 13, 16 could also bepositioned in the blades 11, 12 rather than the body 10 with the sameresult of blade retention. The magnets 13, 16 are retained in the magnetopenings 14, 17 by encasement material 15, 18 being an epoxy or otherencasement material means or mechanical suspension means such as pins.The magnets 13, 16 can be in a plate form or cylindrical or other shape.The magnets 13, 16 are suspended in the slot within the encasementmaterial 15 such that direct contact with the metallic Bore Hole Toolbody 10 is not made or minimized whereby the magnetic force ismaintained. The magnets 13, 16 are positioned to make contact, or nearcontact with the blades 11, 12 when said blades 11, 12 are in a closedposition. The magnets 13, 16 are of sufficient size, shape and magneticstrength and positioned such in the body 10 to allow retention of theblades 11, 12 in a closed position. The magnets 13, 16 are however of alimited size, shape and magnetic strength and positioned such in thebody 10 to allow opening of the blades 11, 12 when adequate fluid ispumped through the Bore Hole Tool or adequate rotation of the drillstring is made to actuate the Bore Hole Tool.

It is therefore to be understood that even though numerouscharacteristics and advantages of the present embodiment have been setforth in the foregoing description, together with the details of thestructure and function of the embodiment, the disclosure is illustrativeonly, and changes may be made within the principles of the embodiment tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed and reasonable equivalentsthereof.

I claim:
 1. A bore hole tool apparatus blade retention system which usesmagnetic means in the body to keep moveable blades in a closed positionwhen not in an operating mode, whereby said magnetic means are of apredetermined strength to retain said blades in a closed position in avertical, angled or horizontal well bore, and whereby said magneticmeans are of a predetermined limited strength to allow the blades toopen to an operating position when rotation of the drill string isactuated or fluid is pumped through the drill string and said toolblades.
 2. In an apparatus according to claim 1 wherein said magneticmeans are positioned adjacent to the distal end of the blades.
 3. In anapparatus according to claim 2 wherein said magnetic means are retainedin the body by hardened fluid encasement material.
 4. In an apparatusaccording to claim 2 wherein said magnetic means are retained in thebody by pin or bolt means.
 5. A bore hole tool blade retention systemwhich uses magnetic means in the blades to keep moveable blades in aclosed position when not in an operating mode, whereby said magneticmeans are of a predetermined strength to retain said blades in a closedposition in a vertical, angled or horizontal well bore, and whereby saidmagnetic means are of a predetermined limited strength to allow theblades to open to an operating position when rotation of the drillstring is actuated or fluid is pumped through the drill string and saidblades.
 6. In an apparatus according to claim 5 wherein said magneticmeans are positioned at the distal end of the blades.
 7. In an apparatusaccording to claim 6 wherein said magnetic means are retained in theblades by hardened fluid encasement material.
 8. In an apparatusaccording to claim 6 wherein said magnetic means are retained in theblades by pin or bolt means.
 9. A bore hole tool apparatus bladeretention system which uses magnetic means in the body to keep moveableblades in a closed position when not in an operating mode, whereby saidmagnetic means are of a predetermined strength to retain said blades ina closed position in a vertical, angled or horizontal well bore, andwhereby said magnetic means are of a predetermined limited strength toallow the blades to open to an operating position when rotation of thedrill string is actuated or fluid is pumped through the drill string andsaid tool blades, wherein said magnetic means are positioned adjacent tothe distal end of the blades and retained in the body by hardened fluidencasement material.